import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        in.nextLine();
        String s = in.nextLine();
        int[] hash = new int[26];
        for (int i = 0; i < s.length(); i++) {
            char ch = s.charAt(i);
            int index = ch - 97;
            hash[index]++;
        }
        int max = 0;
        int index = 0;
        for (int i = 0; i < 26; i++) {
            if (max < hash[i]) {
                max = hash[i];
                index = i;
            }
        }
        boolean flag = false;
        if (n - max > max) {
            flag = true;
            System.out.println("yes");
        } else {
            System.out.println("no");
        }

        if (flag) {
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < 26; j++) {
                    if (i == 0) {
                        if (j != index && hash[j] != 0) {
                            System.out.print((char)('a' + j));
                            hash[j]--;
                            break;
                        } else {
                            continue;
                        }
                    } else {
                        if (j != index && hash[j] != 0) {
                            System.out.print((char)('a' + j));
                            hash[j]--;
                            break;
                        }
                    }
                }
                if(max-- > 0) {
                    System.out.print((char)('a' + index));
                    i++;
                }
            }
        }
    }
}